Lapizuli - 7:50 pm on May 30, 2013 (gmt 0)
Can you clarify what you mean by "design" here? As in, a template? A particular image? A pattern? Was it absolutely, positively owned by the website owner?
As to its being common...if it's an original image owned by the person, I'd say "kind of." A lot of people will say, "Go ahead." However, it depends on what the stakes are for the person. The people who seem most gracious with their IP are people who don't actually own it, or people just starting out or dabbling, who don't realize they have valuable property. A small percentage are committed to sharing their IP as part of a larger ethic of "creative commons."
Personally, at this point in time, I'd charge a fee or insist on gaining a benefit, because my IP is my livelihood and livelihoods aren't thick on the ground these days. But if the IP owner doesn't feel he or she has an investment in the design, then there might be no issue with usage.